The invention disclosed and claimed herein pertains generally to an apparatus for calculating the velocity of sound in a liquid media, and more particularly pertains to such apparatus wherein digital means are employed to calculate sound velocity as a function of conductivity, temperature, and depth.
To effectively employ sonar equipments, as well as to accomplish numerous other activities involving acoustic transmissions in seawater, it is very important to determine the velocity of sound in seawater. A most useful form for such information is a real-time profile of sound velocity versus depth, which may indicate, for example, the refractive effects on sonar waves of different layers of seawater, or the flow of currents through the different layers. As is well known, the velocity of sound at a selected position in seawater is affected by both the temperature and the salinity thereof.
In the past, temperature probes or other thermometric devices have been employed to provide a sound velocity profile by measuring the temperature at various depths in an ocean body. More recently, probes have been used which provide salinity as well as temperature data. Obtaining a profile from such data, however, may require reference to tables and time-consuming computations, whereby the profile is not in real time.
In other types of prior art devices, sound velocity in an ocean media may be directly measured by immersing an active signal producing device in the media, the device radiating signals which are functionally related to the sound velocity at positions through which it passes. In addition to possible errors due to Doppler shift, such active systems may be unsuitable for military purposes where the radiated signals are subject to detection by an unfriendly observer.